• According to both the Classic of Tea (茶經) and the Compendium of Materia Medica (本草綱目), freshly picked tea leaves are inherently cooling in nature. Green tea, which undergoes kill-green processing immediately after picking (non-fermented, non-oxidized), retains this cooling property despite being rich in catechins. For individuals with a “cold” constitution, drinking such tea—especially on an empty stomach—can cause discomfort in the digestive system.

However, these cooling properties can transform into warming ones through fermentation, pan-firing, and roasting techniques. Examples include partially fermented high mountain oolong, Oriental Beauty, fully fermented black teas, and heavily roasted Dong Ding oolong.

“Tea’s nature is cold. It is most suitable for people of refined and frugal character. For conditions such as heat-induced thirst, chest tightness, headaches, eye dryness, limb fatigue, or joint stiffness—just a few sips can rival the effects of nectar or elixir.”
— Excerpt from The Classic of Tea by Lu Yu

“Tea is bitter and cold; it is most effective in reducing internal heat.”
— Compendium of Materia Medica